WELLER Solder Pencil Impedances

Can anyone help with Weller Solder pencil information? I am trying to repair an EC-2002 station w/ EC1204A pencil. I need to understand the connections going to the pencil. I have googled for two days without finding info on these wiring connections.

To be more clear, I am trying to determine what wire on the EC2002 base is connected to what part in the EC1204 pencil. On my base, there is the connector at the left lower corner, looking at the face of the base unit.

This connector has six female pins - I am calling the right upper one (PIN1), the one right under it, (PIN2), and the bottom center one (PIN3), then, continuing in rotation, (PIN4) and (PIN5). The center pin is (PIN6).

Can anyone either tell me what each pin is connected to in the pencil, or can anyone measure the resistance between the pins of their unit and respond with the readings?

I am pretty sure that (PIN1) is one side of the Heating Element, and that (PIN2) is the other side. (My Element measures about 10 0hms.) I think (PIN3) is one side of the RTD Sensor and (PIN4) is the other, but my reading between these pins is infinite. I think (PIN5) is the ESD Gnd. And lastly, I can't determine what is connected to (PIN6), and can't even guess what other connection is used or is necessary in the pencil to require this pin.

Thanks in advance.

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6 pins ??? on an EC2002A base unit? Do you have a center pin (6-pin DIN) on your EC 2002A base unit ?

Weller discontinued the EC base stations (EC1002, EC2002) in 2002 when they moved production to Mexico for 2003.

FIRST, you must be very CAREFUL with the EC series. Weller switched pin assignments from the first generation stations (late

1970s to early 1980s) to the later ones

Hook up these irons wrong -- (24 VAC to the RTC sensor) and the RTC sensor is history !! ($50 mistake)

Are you positive that this is an EC1204A pencil ?? and not the EC 1504 pencil? OR the EC1201A ? which is 5 wire

Spelling and models numbers make a huge difference (see first line)

I am slowly scanning the Weller Tech Sheets that have from that era, I am posting them at BAMA. The EC229 will show you proper wiring of the RTC sensor for the EC1201A iron. Notice that the red and Black wire are the RTC sensor wires within the iron.

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Here is the Weller EC2002A manual (from their web site)

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You should have 2 GOLD socket pins on you EC2002 base -- these designate the RTC sensor pins (Weller did that on purpose) - and you can not purchase those gold pins in small quantities from Amp/Tyco.

IRON cord and handle - colors and pin assignments.

For the EC 1201A IRON,

Black wire goes to # 3 (gold pin) Red wire goes to # 4 (gold pin) Ground/bare wire goes to # 5 White goes to # 2 Yellow goes to # 1

Confirm the GROUND LEAD on your base unit. Unplug from AC line. Check continuity between ground lug of AC line cord and the EC 2002A base unit connector (it will be pin 5, silver colored)

Don't have the correct tools?

AMP/Tyco extractor tool 91136-1 (DigiKey part number: A25081-ND) This tool increased in price by $10 over past few months.

Search on these part number at the AMP/Tyco web page:

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91136-1 (408-7859) 114-10011

Weller (and Pace) soldering stations both use the Amp/Tyco audio/Instrument connectors found on page 292 of the DigiKey On-line catalog. Upper left corner of this page:

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Need help? You may want to call Weller Customer Support in North Carolina -- For this last call, I dealt with Debbie Crizer, Lead Customer Service Rep.

Weller Repair Services

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Dino Chandler manages the Weller Repair Center

g. beat

Reply to
g. beat

OK, your EC2002A base unit has a 6-pin DIN connector (are you sure there is a silver pin in the center connector spot?

The PES51 iron (goes with the WES51 station) uses the center pin (pin 6) instead of (pin 1) for the heater. I am not certain why Weller did this -- BUT it was likely to prevent users from plugging this higher 50 watt PES51 iron into base units with earlier control boards that did not have a large enough Triac (and heat sink).

I have NOT tested - that configuration - it is on my "things to do".

This sounds about right.

That sounds like a bad RTC sensor (platinum BTW) in the iron - it should be around 22 ohms at 23 degrees C

g. beat

Reply to
g. beat

Hi _g. post_

Thanks for the speedy, and informative, reply. Your info was very helpful. I am not aware to what BAMA refers - could you give me a heads up? It seems as if Google should have noticed a treasure trove of Weller tech sheets like you are inputting.

I also need to do a little confessing. I wrote my original post late at nite - that accounts for some dis-information. Secondly, I skirted the truth a little in order to get to the heart of my inquiry. All that did was to confuse you. So, as Paul Harvey says, here is the rest of the story.

My base is an EC2002M-O power unit. The back sticker displays the COOPER logo prominently, so I would guess that the base dates from after the 1980's. It was originally paired with a EC1201A pencil, but I loaned the unit to a technician and when it was returned several months later, he said he could no longer find the pencil. I have a non-functioning EC1503A pencil, so I was trying to get the station back in working order by repairing the EC1503A pencil. This lead to my inspection of the base-unit connector and the discovery of the sixth pin in the Tyco/Amphenol base-unit connector. (I no longer have the EC1201A pencil, so I can't determine if it had a sixth pin.) (By the way - I thought I was pretty observant, but I completely missed the fact that you pointed out - that two of the pins in the connector -pins

3&4- are gold, while the other four are silver.)

Your link to the cooperhandtools manual was helpful, but it does not illustrate the sixth pin in the center of the connector. Mine has a (silver) sixth pin in the center of the other five pins. This pin has a blue wire which connects to the circuit board. I spend quite a while with a lope to confirm that this pin connects to the PIC MPU IC on the circuit board. The schematic of the PIC MPU says that the pin (pin17) is an I or an O pin depending on the programming of the chip. I have no way of referencing the program code, so I can't determine whether this is an input or an output, but I would guess that is is used as an input since there is a 10K (I think) resistor in series with the lead. (i.e.,base connector pin 6 to blue wire to circuit board to 10K to pin

17 of the PIC processor.) One unsupported quess is that this is an input and that it is used to implement a software zero-crossing detector to control the TRIAC turn-on point, but, this seems like a really round-about way to make the connection for a zero-crossing signal. If you have any ideas, I would really appreciate hearing them.

I guess my real question at this point is, do you think fixing the EC1503A pencil (replacing the RTD) is a way to go here? Do I need to worry about the center pin at all? My other soldering station is a cheapo Unger, and I really miss the Weller.

Thanks - MashBrain

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BAMA is the acronym for BoatAnchor Manual Archive. Boatanchor is the "slang" term used for old tube-type radio and short wave receivers and equipment. It was started by Ken Grimm in Lynchburg, VA. It is a valuable repository for manual of many companies that are no longer in business or large companies that have exited the electronics industry. Most of this equipment is 1930's through 1960's

Ken was kind enough to include the earlier Weller information (discontinued products).

A new EC 1201A pencil cost $ 100, I don't loan my tools - too many sticky fingers (can't find it ) these days. Ask him for $100 to replace that iron - and he will find it in a box.

BTW, a new EC1503B iron is $ 130 .. so yes I think it is worth getting fixed properly. I assume that your "A" has a white silicon cord (may be only difference)

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I have not worked on the EC 1503 pencil - it was a high wattage pencil. Weller is the best to ask about availability for those parts. Wassco lists a EC263B Sensor Assembly (WAS-02-18901) at $58 That may be the correct part

I usually use Action Electronics or Wassco for many parts orders, BUT thee are MANY other good dealers / distributors throughout the US.

You can also call Weller for parts directly (use direct number below) - or they can tell you of local dealer / distributor near you

Cooper Tools / Weller

1000 Lutkin Road Apex, NC 27502 Toll free number: (800) 476-3030 ext. 2 Direct (919) 362-7542 FAX: (919) 387-2640

Action Electronics (Northern CA)

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Wassco (Southern CA)

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I do have a new wiring harness (EC270) for the station's control board in front of me (arrived from Weller yesterday). The blue wire is there, I have removed it for retro-fit repairs.

On earlier EC1002 stations that I have opened up - this wire was cut and not installed to the iron connector.

The Pace soldering irons (PS-80, PS-90) use the middle pin in the 6-pin DIN connector -- just like the new WES51 station. I am almost positive that Pace uses that as a heater connection -- BUT I would have to pull that documentation up to see how they are wired.

In the PES51 iron (for WES51 station)- that wire is used for the heater (and pin 1 is blank)

DVM or VOM (Scope -- if you have one)

I am looking at a block diagram of a Weller Thermolock (circa 1987) and that seems likely. The zero crossing (+/-) firing drives the Gate Driver - which is interfaced to the charge switch (RTD sensor control) and the Triac.

I pulled out a spare EC271 (EC1002 control board - latest version). Blue pin goes to a breakout of 2 resistors (10K and 100K) and a capacitor.

The 100K resistor line goes onto larger 3-pin surface mount component: W0242 MC7805C3

That appears to be a 5 volt voltage regulator, So the blue lead (through the 100K resistor) goes to the output lead on the regulator, the center pin is cut (no connection) and the input lead goes through diode (looks to be 1N4001) and

100 ohm resistor -- this ends up at 24 VAC feed from Red wire (24 VAC secondary) of transformer in base unit. (This is also the lead to pin 1 on the base's front connector for iron).

Looks like pin 1 is for temperature compensating?

YES, a new EC1503B iron is $ 130 .. I think it is worthwhile getting fixed properly. If the heater is OK and you are sure that the 2002 base unit is OK (you can read the voltages in the 2002 manual for troubleshooting to verify) The RTD, as you see is a significant cost (1/2) of the overall iron's cost.

Ungar made some good stations. Parts for these are still available - Action Electronics in California was one of Ungar largest west coast resellers in

1990s (they have good knowledge of parts and service for them).

g. beat

Reply to
g. beat

I just checked Weller Repair service (Dino chandler) prices for your EC

1503B iron - its only $50 !! .

that is actually a bit cheaper than buying the RTD part ($55) and repairing it yourself !!


Reply to
g. beat

Here is the Weller Warranty and Repair (out of warranty) Price sheet.

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Many of these prices are quite good -- in some instances - it is cheaper than individual parts - and you get the labor for free. You can e--mail the service center (Dino Chandler, manager) for specific requirements or repairs.

g. beat

Reply to
g. beat

Hi again:

Again, thanks for _all_ the info. I need to sit back and digest all of it now. I will probably try a new pencil - I'll have to check the comparative prices for the EC1201A, EC1302A, and the EC1503A units. The stuff I'm doing nodays, the EC1201A is adequate, but why have an adjustable unit if I don't have the hi-watt pencil if/when I need the extra heat.

And again, I agree with your info about the circuit board components. The RC network on the blue lead is as you describe. I was again trimming my description to a too-bare minimum in order to talk about something else. mea culpa.

One other point of curiosity - I thought the PACE pencils used a different RTD - about 100 ohms at 75F. Do you know where I can check on that?

Well, if anything particularily interesting develops, I'll post a follow-up, but at this point, it seems like this has turned into a "tear it down, fix the broke stuff, put it back together, and use it for another 25 years".

It is really a pleasure to put out a feeler like this and get back a prompt, knowledgeable, definitive answer. Thanks again.


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IF you have a library of "ET" tips -- the EC 1201A is a great iron - and it is the iron that I include with the EC 1002 stations I refurbish. Shop around, but it will cost you a "C' note for a new one -- wherever you buy it. Plenty of Internet sites that will sell this -- but chekc is they actually hsave it IN STOCK !

I still would get the $$ out of your technician who lost your EC 1201A.

The EC1503A is a "different" duck - it has the highest wattage (42 - 45 watt) of the 3 you mentioned and was built for point-to-point, power supply building and soldering of "larger mass" (electrical component, etc.). For $50 it is an easy fix - but depnds on your usage.

You might find a few dead EC 1201A irons (place a want ad). If heater is not bad ($20 repair) -- then it is the RTD sensor ($50) -- then its 1/2 price of a new one.

The EC 1302B is a sweet iron for small surface mount work. I rewired an older EC1301 to work with my stations, at 20 watts it is just enough for touch-up on those small resistors

I have never asked Weller if the PES51 (at $30) could be rewired (plug change) for the EC2002 base units. That would be an interesting question for Weller.

I have now seen 4 different board layouts (analog dial) for the "EC" series control boards. From the 1980s ceramic surface mount boards - that can crack (due to physical shock to base - dropping) to the most recent PIC processor with good sized heat sink on Triac.

I think this last design I received last week -- with a green LED -- are actually WES50 / 51 control boards -- using the older harness. I will have to open up a WES51 station sometime to confirm.

You may be correct. There are some differences between the SP-1A and PS-80 / PS-90. I have one, I just have not taken the time to measure the RTD sensor resistance at 23 C

I once acquired a Pace base unit (ST-25) that has an EC 1201A attached to it. I separated them -- and matched them to their proper configurations - but they were both okay. That is the problem with these equipment auctions and sales - mismatching of items.

g. beat

Reply to
g. beat

One other option to consider. Place the EC 2002 on eBay for sale, make a few dollars.

Go out and purchase a Weller WES51 or WESD51, if you have other ET tips on your workbench. Those tips are same as used in these 2 new stations. You will pay the same amount of money for one of these new stations as buying a new EC1201A iron ! The replacement PES51 iron for those base units sells for $30 - integrated sensor and heater (cuts costs).

Tied of Weller? then the Hakko 936-12 is a good buy (analog dial) for around $ 90.

g. beat

Reply to
g. beat

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